Sump overflowing after installing UV (with my drawing)

[Miami Reef]

I can really use some help here.

I drew a picture that explains everything I’m dealing with.

First, a little anatomy of my tank: I have a sump, then the tank is above the sump, then I have the top of the canopy which is above the tank - kind of like a “roof”.

Original tank setup:
One return pump. No UV nor UV plumbing.

Today I plumbed a UV sterilizer. I put the separate UV pump in the sump and I make the water flow through the top of the canopy and then into the Display Tank, like how the people nowadays run 2 returns.

I turned on the pump for the UV for the first time and my sump did not run dry. It had the same amount of water the entire time. This whole thread was in the span on 10 minutes, so it’s impossible my tank filled with extra water…

Anyway, when I closed both of the pumps (Return & UV) the sump level slowly and slowly rose until it started overflowing. It wasn’t drastic because I was watching and closed it right away, but I don’t know how much more the sump would have overflowed if I didn’t turn the units back on.

Right now my tank is just running with only the return pump, and it’s working as it used to be, but I want to plumb my UV and use it because I’m dealing with a big bacterial bloom and I have lots of fish.

PS: I made a hole below the water line of the UV outlet (to prevent back siphon). Although that stopped the future siphon, I STILL had extra water trickling from the UV tubing presumably from the top of the canopy that holds all the water. It’s a pretty tall distance from the sump to the top of the tank (250 gallon tank) so there can definitely be water stored in the tubings.


So what’s the cause of this? My UV must remain above the canopy because it’s the only place it fits (trust me, I’ve tried EVERYWHERE else.) So they only thing I can do is manipulate where the inlet and outlets of the UV are.

Please help!

 

[Smite]

When you say closed both pumps does that mean you turned them off? Sounds like the back siphon is just too much for your sump to handle. the hole may not be large enough for the siphon to break completely or at least not quick enough. Would it be possible to put a elbow fitting on the return (maybe even with a loc-line nozzle) so when on it just adds surface movement but when off it can't siphon much out of the display?

Another option might be a check valve on the UV return line.

 

[Miami Reef]

When you say closed both pumps does that mean you turned them off? Sounds like the back siphon is just too much for your sump to handle. the hole may not be large enough for the siphon to break completely or at least not quick enough. Would it be possible to put a elbow fitting on the return (maybe even with a loc-line nozzle) so when on it just adds surface movement but when off it can't siphon much out of the display?

Another option might be a check valve on the UV return line.

Yes, when I say I closed the pumps, I meant that I turned them both off.

I can drill the hole bigger on the UV pipe that meets the water.

What is “elbow fitting on return”? Do you mean the PVC elbows? If so, both the UV and Return have elbow fittings on the ends of the PVC tubing inside the display tank.

 

[Miami Reef]

My return has a check valve. The UV doesn’t.

 

[Smite]

Yes, when I say I closed the pumps, I meant that I turned them both off.

I can drill the hole bigger on the UV.

What is “elbow fitting on return”? Do you mean the PVC elbows? If so, both the UV and Return have elbow fittings on the ends where the line ends inside the display tank.

That may be an option, I'd be looking for a more fail-safe solution. Sounds like the fittings are there, can you set them up so the outlet is only half way below the waterline (opening of pipe or nozzle) without excessive splashing? That would cause siphon to break almost immediately.

The check valve would buy you some time but I don't trust those for a perfect seal.

 

[Miami Reef]

That may be an option, I'd be looking for a more fail-safe solution. Sounds like the fittings are there, can you set them up so the outlet is only half way below the waterline (opening of pipe or nozzle) without excessive splashing? That would cause siphon to break almost immediately.

The check valve would buy you some time but I don't trust those for a perfect seal.

When my return line was slightly below water surface it caused a LOT of large bubbles/microbubbles. When I extended the tube lower the microbubbles stopped. Was this a coincidence? The opening was fully submerged in water.

 

[Miami Reef]

I don’t think the UV back siphoning is the issue. I think there’s just a LOT of water left from the entire path of tubes. It’s a really vertical and steep path up. Breaking the siphon isn’t going to stop it from overflowing.

 

[Miami Reef]

This is a picture. The UV goes from sump all the way to the top left (it’s vertical climb) then it’s a horizontal slope that passes from the left to the right side, and then it drops on the right side on the tank.

 

[Smite]

When my return line was slightly below water surface it caused a LOT of large bubbles/microbubbles. When I extended the tube lower the microbubbles stopped. Was this a coincidence? The opening was fully submerged in water.

That could be caused by surface agitation but usually you'll get some larger bubbles from that.
When it comes to siphoning from the tank, your siphon will pull until your display reaches the bottom of that pipe, or if a 90 elbow pointing across the surface until about 1/2 way down the opening. It will slurp for a few minutes too as the siphon starts to break. I think you're problem is, the longer the run the harder it is to break siphon. Gravity will keep starting it back up unless a large amount of air is allowed in at once.

So if you want to do the math to figure out how much of the tank with actually siphon take the inches of the pipe below water surface and multiply that by the length and width of your tank in inches and divide by 231 for volume.

So say your tank is a 8x2 footprint and the return is 1" below the surface. You're 1x96x24/231 you're going to siphon roughly 9-10 gallons down to your sump before siphon break. It adds up quick. You may be in need of some type of nozzle tip to help with the bubbles and allow you to turn the return very close to the surface in the display.

 

[Smite]

This is a picture. The UV goes from sump all the way to the top left (it’s vertical climb) then it’s a horizontal slope that passes from the left to the right side, and then it drops on the right side on the tank.

Is that pipe to the left with the T fitting a drain or return? If that's a return that's how low your display will drain before breaking siphon.

That is a lot of head feet to drain back but I'd imagine you have a decent sized sump on a 250g right? Could maybe a gallon, 2 at max make the difference?

EDIT: Head feet referring to the amount of pipe to UV*

 

[Greg P]

I run my return lines with locline, and have them placed so they are horizontal with the water level.
Helps with stopping back siphoning

 

[Smite]

I'm thinking your return is on the right and the uv return on the left judging by your sketch. You haven't experienced this in the past due to the check valve on your return.

 

[Miami Reef]

First, this picture is a few months old. My UV plumbing is not like that picture. It was mainly to demonstrate the height of my tank.

When I close my UV I hear a gurgling sound. I think the leaking issue happened because I was trying to drain the UV so I can add the bulbs (I ran without bulbs to test leaks).

I was tilting the UV so maybe I dialoged water from the horizontal area?

 

[Miami Reef]

This is my actual return line.

A more recent picture:

 

[Smite]

I've drained tanks with a long garden house out to my curb. I was able to pull the hose from the display and transfer it to the sump. That took a few seconds and the siphon started back up, due to the water still in the pipe. Longer the run, the more air and time it takes to break. A small hole isn't going to do alot.

What might help, cut another tee fitting at the water surface. The majority of the water will still flow down to your current location and minimal amounts of water will leave at the surface tee, but come siphon it will suck enough air to break from the surface tee.

 

[Smite]

This is my actual return line.

A more recent picture:

so that 90 is probalby 3" below water surface, you could be trying to drain 30+ gallons to your sump.

Do a test if you have another elbow and small section of pipe. Kill flow and insert the elbow with a small section to get above water surface, see if the sump still overflows.

Aside from that I think you're only option is a check valve or changing the water level in the sump drastically to handle the water volume when pumps are off, whether its from the conduits or the tank.

 

[Miami Reef]

So you want me to drill a much bigger hole below water surface? I can do that.

 

[Smite]

So you want me to drill a much bigger hole below water surface? I can do that.

I think for that to work with the amount of pipe you have plumbed in to your UV run, you need to cut in another T fitting at the surface. Cut in so the perpendicular outlet is right at water surface, that should give you a near instant siphon break while limiting bubbles.

I'm sure someone else will chime in and confirm or have a better/easier solution. That's just what I would do.

 

[Greg P]

This is my actual return line.

A more recent picture:

Have a look at my picture in post #11

 

[Greg P]

No noise from the return lines and helps with surface agitation/aeration.
I've never had any back-siphoning with this style of setup. I do run a check valve on my return line, but only to keep the pipe filled so there is no splashing when the pump is turned back on. I don't rely on the check valve to stop any flooding.